Chabad.org — English translation + Rashi
Torah Temimah points to Menachos 58a.
E-Daf.com — Menachos 58a
HebrewBooks / Shas PDF
English: Might one think: since the two loaves and bikkurim are called first-offering, therefore if another offering has already been brought they may not be brought? The verse says “you shall offer.”
Ribbuy despite prior offerings — the command to offer remains in force even when other korbanot have already been brought.
Being called “first” does not bar them when other offerings precede. The Torah’s insistence “you shall offer” keeps the two loaves and bikkurim valid even if other sacrifices have already been brought that day.